Increments for moving objects gets messed up?
You've accidentally enabled Snapping during transform (the little magnet icon) with Increment setting. So it's automatically trying to snap to the "grid" of the world when you move it around.
It's a super handy feature when modeling. 

You can read more here Transform Snapping

Hope this clears it up. I highly recommend reading up on this feature and playing around with it, it's SUPER useful when polymodeling and moving things around.